As described in Patent Publication 1, for example, an electrically operable micropipette (hereinafter referred to as “electrical pipette”) includes, in a vertically long cylindrical main casing, a motor and a cylinder into which a piston is inserted. The driving of the motor which is activated by means of an operation switch disposed in the main casing while a handgrip of the main casing is gripped vertically moves the piston in the cylinder. The vertical movement makes positive and negative pressures in the cylinder to suck and discharge a predetermined amount of liquid into and from a chip equipped at the front end of the main casing.
In order to perform the sucking and discharging operations, a display-operation section is disposed at the base end of the main casing to establish a volume parameter and an operation mode of the device. At the base end of the main case in which the display-operation section is positioned, an electric board for electrically controlling the motor depending on the respective setups of the display-operation section, and an electric source for driving the electric board and the motor are disposed. Further, a release switch for detaching the chip and a finger rest acting as a holding assist during an operation and a stopper during a non-operation are disposed in the main casing.